1. Field of the Invention
This invention relates to medium rate of fire armaments and more particularly to an improved externally powered automatic gun of comparatively low weight and of relatively simple and reliable design, particularly adaptable for use on aircraft, and method of operating the same.
2. Description of the Prior Art
Single barrel externally powered gun systems are known and are characterized by complicated mechanisms and sequences for the firing cycle which usually includes loading, locking, firing, unlocking, and ejecting the spent round. Where rates of fire of 500 to 1000 rounds per minute per barrel are needed, the weapons heretofore designed are either of the Gatling gun variety, i.e. multiple barrels rotated into a battery position, or a single barrel which is cycled in a reciprocating type of movement into and out of a battery position. In each case, the systems are relatively complex and expensive because of the relatively large number of moving parts and the necessity to move the barrels.
When a Gatling system is used, there is a varying tangential velocity imparted to the projectile because of start-up, firing, or changing the barrel cluster's rate of fire. Additionally, in a Gatling mechanism the barrels are generally pointed inward at the muzzle end and variations in the angular position of the barrel at the moment of firing result in different impact points.
In the case of cycled barrel armament and a Gatling-type armament, a considerable mass must be moved and overall, the system provides a relatively large profile, a factor which may be of significance in instances of airborne use. For example, aerodynamic drag, weight and complexity of mechanism are factors when such weapons are to be used as armaments in armed helicopter mountings. The moving barrels of prior art systems has also created problems because of the infrared signature of high rate of fire weapons and the difficulty of effectively insulating the barrels, the principal infrared source.
Thus, a simple relatively inexpensive and reliable gun system of the externally powered type, which is simple in operation, offers advantages, especially for airborne use. By this invention, a gun system is provided which is lighter in weight, has reduced profile for lowered aerodynamic drag, is comparatively inexpensive and is as reliable as the prior art systems. Moreover, the gun system of this invention offers the additional advantages of shorter time to reach full rate of fire, long firing burst capability, prevention of double round feeding and safety against "cook off", i.e. firing due to presence of a round in a heated firing chamber. These advantages are achieved by a gun having substantially less parts than the prior art systems e.g. those gun systems known as the XM-188 and XM-140. Moreover, the sequence and timing of the gun function is controlled in a novel manner by an improved control mechanism.